The research objective is to understand the regulation of juvenile hormone (JH) synthesis by the corpora allata (CA). The model system to be studied is the reproductive cycle of the female viviparous cockroach Diploptera punctata in which egg development is precisely controlled by cycles of juvenile hormone synthesis. The project will test the hypothesis, establised by previous studies on this system, of a dual control: an inhibitory center which requires intact nerves and a stimulatory center which can act humorally. In addition it will investigate the feedback from the CA and ovaries to the control centers. A direct measurement of JH synthesis by the CA will be made using an established short term in vitro radiochemical method. The CA will be subjected to altered environments in vivo by transplantation and in vitro, by use of explanted tissue or extracts thereof, in order to establish pathways of control. Correlated morphological evidence for neurosecretory control will be sought in studies of the CA and neurosecretory tissues using several techniques including histochemistry and electron microscopy.